The invention relates to electronic components, and more particularly resistance devices formed on a resistor core.
The resistors in question consists of a resistive film applied to an insulating core material, such as a ceramic. Leads are attached to opposed ends of the resistor core, and the particular value of the resistor is determined by the resistivity of the coated film over the resistor core between electrical contact points of the opposed ends. In order to provide a secure mechanical connection between the leads and the resistor core, caps are attached to the leads and surround the opposed ends of the resistor core. Such caps provide both electrical and mechanical connection between the resistor film and the leads.
For high value resistors, that is, for resistance in excess of 1000 ohms, it is generally not critical that the cap be secured to the resistor core at a critically predetermined point. The reason is that a relative displacement between the cap and resistor core will not substantially change the value of the resistor. This is not the case, however, with smaller valued resistors, in which the slightest shift or change of the electrical connection point between the cap and the resistive core will mean a large change in the total value in the resistor.
The prior art resistors have used gold as an end termination coating for securing the cap to the resistor element. In addition to being expensive, gold does not provide a suitably reliable electrical and mechanical connection.